The lamina also processes information sent from other parts of the brain regarding blood pressure, blood volume and other important aspects of homeostasis. Diseases that can Cause Excessive ThirstExcessive or constant thirst are signals that we need to pay close attention to. Kidney DiseaseSymptoms:ThirstChanges in urinationSwelling (legs, face)FatigueNauseaHow to tell:Abnormal kidney blood tests (creatinine, BUN)Urine protein or bloodOften other systemic symptoms5. Excessive blood loss (or hemorrhage) calls for replacement of fluids in the form of donated blood and various formulations of IV fluids. Infants, children, young people and adults of all ages can suffer when the causes of excessive thirst are not addressed.